Monitoring of intrathoracic volumes in induced supranormal cardiac output

Background

Induced whole body hyperthermia (WBH) up to 42°C leads to hypercirculation, large fluid shifting and a high demand of intravascular fluids. This study was performed to evaluate several parameters of systemic and intrathoracic hemodynamics during such a condition of hypercirculation with high cardiac output and low vascular resistance.

Methods

A combination of reflexion photometry and thermodilution (COLD Z-021-System, Pulsion, Germany) was used to obtain mean arterial pressure (MAP), cardiac output (CO), global end-diastolic volume index (GEDVI), intrathoracic blood volume index (ITBVI), total blood volume index (TBVI), right ventricular end-diastolic volume index (RVEDVI), right heart end-diastolic volume index (RHEDVI), left heart end-diastolic volume index (LHEDVI), pulmonary blood volume index (PBVI) and extravascular lung water index (EVLWI) at 37°C, 41.8°C and 39°C in 26 patients with metatased cancers during 51 WBH treatments. WBH was induced by infrared radiation (Iratherm 2000). Hemodynamics at 41.8°C and 39°C were compared with the initial values using Wilcoxon rank sum test for linked random samples.

Results

Compared with the initial values at 37°C significant increases of CO, GEDVI, ITBVI, TBVI, RVEDVI, RHEDVI and PBVI and a significant decrease of MAP could be found at 41.8°C. For LHEDVI and EVLWI no significant changes were observed. Some of these parameters were still significantly changed during the cooling-down phase at 39°C, but, with exception of EVLWI, all parameters showed a clear tendency to pre-treatment levels. Only EVLWI showed a slight tendency to further increase during the cooling-down phase.

Conclusions

Induced hyperthermia results in significant changes of cardiac output, intracardial and intrapulmonary volumes. Therefore monitoring of these parameters seems to be useful in risk patients and in other conditions of hypercirculation.